Accommodating intraocular lens having peripherally actuated deflectable surface and method

ABSTRACT

An accommodating intraocular lens is provided in which a deflectable lens element is anchored to a substrate along its optical axis to define a fluid filled space. Fluid-filled haptics disposed in fluid communication with the space vary the fluid volume in the space responsive to forces applied by the ciliary muscles, thereby causing the periphery of the lens element to deflect relative to the substrate and changing the optical power of the intraocular lens.

CROSS-REFERENCE

This application is a continuation of U.S. application Ser. No.11/715,221, filed Mar. 6, 2007; which is a continuation of U.S.application Ser. No. 11/252,916 filed Oct. 17, 2005, now U.S. Pat. No.7,217,288; which is a continuation-in-part of U.S. application Ser. No.10/971,598, filed Oct. 22, 2004, now U.S. Pat. No. 7,261,737; which is acontinuation-in-part of U.S. application Ser. No. 10/734,514, filed Dec.12, 2003, now U.S. Pat. No. 7,122,053; which claims the benefit ofpriority from U.S. Provisional Application No. 60/433,046, filed Dec.12, 2002; all of which are incorporated by reference in their entiretyas if fully set forth herein.

BACKGROUND OF THE INVENTION

Cataracts are a major cause of blindness in the world and the mostprevalent ocular disease. Visual disability from cataracts accounts formore than 8 million physician office visits per year. When thedisability from cataracts affects or alters an individual's activitiesof daily living, surgical lens removal with intraocular lens (IOL)implantation is the preferred method of treating the functionallimitations. In the United States, about 2.5 million cataract surgicalprocedures are performed annually, making it the most common surgery forAmericans over the age of 65. About 97 percent of cataract surgerypatients receive intraocular lens implants, with the annual costs forcataract surgery and associated care in the United States being upwardsof $4 billion.

A cataract is any opacity of a patient's lens, whether it is a localizedopacity or a diffuse general loss of transparency. To be clinicallysignificant, however, the cataract must cause a significant reduction invisual acuity or a functional impairment. A cataract occurs as a resultof aging or secondary to hereditary factors, trauma, inflammation,metabolic or nutritional disorders, or radiation. Age-related cataractconditions are the most common.

In treating a cataract, the surgeon removes the crystalline lens matrixfrom the lens capsule and replaces it with an intraocular lens (“IOL”)implant. The typical IOL provides a selected focal length that allowsthe patient to have fairly good distance vision. Since the lens can nolonger accommodate, however, the patient typically needs glasses forreading.

More specifically, the imaging properties of the human eye arefacilitated by several optical interfaces. A healthy youthful human eyehas a total power of approximately 59 diopters, with the anteriorsurface of the cornea (e.g. the exterior surface, including the tearlayer) providing about 48 diopters of power, while the posterior surfaceprovides about −4 diopters. The crystalline lens, which is situatedposterior of the pupil in a transparent elastic capsule supported by theciliary muscles, provides about 15 diopters of power, and also performsthe critical function of focusing images upon the retina. This focusingability, referred to as “accommodation,” enables imaging of objects atvarious distances.

The power of the lens in a youthful eye can be adjusted from 15 dioptersto about 29 diopters by adjusting the shape of the lens from amoderately convex shape to a highly convex shape. The mechanismgenerally accepted to cause this adjustment is that ciliary musclessupporting the capsule (and the lens contained therein), move between arelaxed state (corresponding to the moderately convex shape) to acontracted state (corresponding to the highly convex shape). Because thelens itself is composed of viscous, gelatinous transparent fibers,arranged in an “onion-like” layered structure, forces applied to thecapsule by the ciliary muscles cause the lens to change shape.

Isolated from the eye, the relaxed capsule and lens take on a sphericalshape. Within the eye, however, the capsule is connected around itscircumference by approximately 70 tiny ligament fibers to the ciliarymuscles, which in turn are attached to an inner surface of the eyeball.The ciliary muscles that support the lens and capsule therefore arebelieved to act in a sphincter muscular mode. Accordingly, when theciliary muscles are relaxed, the capsule and lens are pulled about thecircumference to a larger diameter, thereby flattening the lens, whereaswhen the ciliary muscles are contracted, the lens and capsule relaxsomewhat and assume a smaller diameter that approaches a more sphericalshape, thereby increasing the diopter power of the lens.

As noted above, the youthful eye has approximately 14 diopters ofaccommodation. As a person ages, the lens hardens and becomes lesselastic, so that by about age 45-50, accommodation is reduced to about 2diopters. At a later age the lens may be considered to benon-accommodating, a condition know as “presbyopia”. Because the imagingdistance is fixed, presbyopia typically entails the need for bi-focalsto facilitate near and far vision.

Apart from age-related loss of accommodation ability, such loss isinnate to the placement of IOLs for the treatment of cataracts. IOLs aregenerally single element lenses made from a suitable polymer material,such as acrylics or silicones. After placement, accommodation is nolonger possible, although this ability is typically already lost forpersons receiving an IOL. There is significant need to provide foraccommodation in IOL products so that IOL recipients will haveaccommodating ability.

Although previously known workers in the field of accommodating IOLshave made some progress, the relative complexity of the methods andapparatus developed to date have prevented widespread commercializationof such devices. Previously known devices have proved too complex to bepractical to construct or have achieved only limited success, due to theinability to provide accommodation of more than 1-2 diopters.

U.S. Pat. No. 5,443,506 to Garabet describes an accommodatingfluid-filled lens wherein electrical potentials generated by contractionof the ciliary muscles cause changes in the index of refraction of fluidcarried within a central optic portion. U.S. Pat. No. 4,816,031 to Pfoffdiscloses an IOL with a hard PMMA lens separated by a single chamberfrom a flexible thin lens layer that uses microfluid pumps to vary avolume of fluid between the PMMA lens portion and the thin layer portionand provide accommodation. U.S. Pat. No. 4,932,966 to Christie et al.discloses an intraocular lens comprising a thin flexible layer sealedalong its periphery to a support layer, wherein forces applied to fluidreservoirs in the haptics vary a volume of fluid between the pluralityof layers to provide accommodation.

Although fluid-actuated mechanisms such as described in theaforementioned patents have been investigated, commercially availableaccommodating lenses, such as developed by Eyeonics, Inc. of AlisoViejo, Calif., rely on ciliary muscle contraction of the IOL haptics tovault the optic towards or away from the retina to adjust the focus ofthe device.

One promising line of IOL apparatus and methods is disclosed in commonlyassigned U.S. Patent Publication 2005/0119740 A1 to Esch et al. There,apparatus and methods are described in which a patient's vision may beimproved by implantation of an IOL having one or more pistons disposedat or near the center of a deformable surface of the IOL. Due to thepotential for reflections to arise during movement of the piston nearthe optical axis of the IOL, it may be desirable to relocate theactuators to a peripheral portion of the IOL.

In view of the foregoing, it would be desirable to provide apparatus andmethods that restore appropriate optical focusing power action to thehuman eye.

It further would be desirable to provide methods and apparatus wherein adynamic lens surface may be effectively manipulated by the ciliarymuscular mechanisms within the eye.

It still further would be desirable to provide methods and apparatusthat utilize pressure applied by the accommodating muscular action todeform an optical surface of the IOL. In particular, it would bedesirable to provide an IOL in which muscular pressure may be appliedthrough one or more actuators to obtain a mechanical advantage.

It is yet further desirable to provide methods and apparatus that reducethe possibility of reflections within the IOL arising due to movement ofmechanical actuators situated along or near the optical axis of the IOL.

SUMMARY OF THE INVENTION

In view of the foregoing, it is an object of the present invention toprovide apparatus and methods that restore appropriate optical focusingpower action to the human eye.

It is a further object of this invention to provide methods andapparatus wherein a dynamic lens surface may be effectively manipulatedby the ciliary muscular mechanisms within the eye.

It is another object of the present invention to provide methods andapparatus that utilize pressure applied by the accommodating muscularaction to deform an optical surface of the IOL.

It is a further object of this invention to provide methods andapparatus for applying muscular pressure, through one or more actuators,to obtain a mechanical advantage in altering the optical parameters ofone or more surfaces of the IOL.

It is yet a further object of this invention to provide methods andapparatus that reduce the possibility of reflections within the IOLarising due to movement of mechanical actuators situated along or nearthe optical axis of the IOL.

These and other objects of the present invention are accomplished byproviding a lens in which force exerted on a fluid reservoir by themovement of the ciliary muscles, zonules and capsule is applied to adynamic optical surface.

In accordance with the principles of the invention, an IOL is providedhaving a dynamic lens surface that deflects in response to forcesapplied to one or more haptics. In a preferred embodiment, thedeformable surface is anchored to a substrate near the optical axis ofthe IOL, and is deformed from an accommodated state to an unaccommodatedstate by deflection of the periphery of the deformable surface. In thismanner, the IOL of the present invention reduces the possibility thatlight entering the IOL may be reflected due to movement of an actuatordisposed at or near the optical axis of the IOL.

In accordance with another aspect of the present invention, a reservoircontaining a fluid is disposed in a haptic portion of the IOL, so thatcompressive forces arising due to movement of the ciliary muscles aretransmitted via the haptic portion and fluid to deform the dynamicsurface, thereby varying the accommodation of the IOL.

Methods of using the lens of the present invention also are provided.

INCORPORATION BY REFERENCE

All publications and patent applications mentioned in this applicationare herein incorporated by reference to the same extent as if eachindividual publication or patent application was specifically andindividually indicated to be incorporated by reference.

BRIEF DESCRIPTION OF THE DRAWINGS

The novel features of the invention are set forth with particularity inthe appended claims. A better understanding of the features andadvantages of the present invention will be obtained by reference to thefollowing detailed description that sets forth illustrative embodiments,in which the principles of the invention are utilized, and theaccompanying drawings of which:

FIG. 1 is a sectional side view of a human eye;

FIGS. 2A and 2B are, respectively, detailed sectional side views of thelens and supporting structures of FIG. 1 illustrating relaxed andcontracted states of the ciliary muscles;

FIGS. 3A and 3B are, respectively, an exploded perspective and sidesectional view taken along line 3B-3B of an exemplary embodiment of anaccommodating intraocular lens described in U.S. Patent Publication2004/0169816 A1;

FIGS. 4A-4C are schematic views of illustrating the use of fulcrumpoints to facilitate deflection of an optical surface as described inU.S. Patent Publication 2004/0169816 A1;

FIGS. 5A-5D are, respectively, a perspective view, a top view, across-sectional perspective view taken along line 5C-5C, and an explodedperspective view of an embodiment of an accommodating intraocular lensof the present invention; and

FIGS. 6A-6D are, respectively, a perspective view, a cross-sectionalperspective view taken along line 6B-6B, an exploded perspective view,and a top transparent view of an alternative embodiment of anaccommodating intraocular lens of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

The present invention is directed to an in-situ accommodatingintraocular lens system. In accordance with the principles of thepresent invention, methods and apparatus are provided wherein a lens hasan optic element comprising a deformable surface and an actuator thatselectively deflects the deformable surface to change an optical powerof the lens. In accordance with the principles of the present invention,a central portion of the deformable surface is anchored to a substrateand the lens transitions between the accommodated and unaccommodatedpositions by deflection of a peripheral region of the deformablesurface.

Referring to FIGS. 1 and 2, the structure and operation of a human eyeare first described as context for the present invention. Eye 10includes cornea 11 pupil 12, ciliary muscles 13, ligament fibers 14,capsule 15, lens 16 and retina 17. Natural lens 16 is composed ofviscous, gelatinous transparent fibers, arranged in an “onion-like”layered structure, and is disposed in transparent elastic capsule 15.Capsule 15 is joined by ligament fibers 14 around its circumference tociliary muscles 13, which are in turn attached to the inner surface ofeye 10.

Isolated from the eye, the relaxed capsule and lens takes on a sphericalshape. However, as described hereinabove, when suspended within the eyeby ligament fibers 14, capsule 15 moves between a moderately convexshape (when the ciliary muscles are relaxed) to a highly convex shape(when the ciliary muscles are contracted). As depicted in FIG. 2A, whenciliary muscles 13 relax, capsule 15 and lens 16 are pulled about thecircumference, thereby flattening the lens. As depicted in FIG. 2B, whenciliary muscles 13 contract, capsule 15 and lens 16 relax somewhat, thusallowing the lens and capsule to assume a more spherical shape, and thusincreasing the diopter power of the lens.

As discussed hereinabove, commercially available accommodating lenses,such as the Crystalens device by Eyeonics, Inc., Aliso Viejo, Calif.,typically involve converting diametral movements of the ciliary muscleinto forward and backward movement of the optic portion of the IOLrelative to the retina. This approach is thought to be required because,following extraction of a cataract-effected lens, the capsular bag isvery loose, and the ligament fibers that couple the capsule to theciliary muscles are no longer in tension. Devices such as the Crystalensthus do not employ the natural accommodation mechanisms described above,but instead rely directly on radially inward compressive forces appliedby the ciliary muscle to the haptics of the IOL.

In accordance with principles of the present invention, compressiveforces applied to the haptics of the IOL are employed to provideaccommodation by deflecting a dynamic surface of the lens. Thisdeflection causes a variation in the optical path of light passingthrough the lens, thus altering its optical parameters.

Referring now to FIGS. 3A and 3B, an embodiment of the accommodating IOLof U.S. Patent Publication No. 2004/0169816 A1 is described. In thatdevice, a flexible layer situated between two fluids of differentindices of refraction is deflected to vary the accommodating power ofthe lens. IOL 20 comprises substrate 21, actuator element 22, flexiblelayer 23 and anterior element 24, assembled in a sandwichedconfiguration.

Substrate 21 preferably comprises a sturdy transparent polymer andincludes posterior lens 25, haptics 26, lower chamber 27, reservoirs 28,passageways 29 and lower relief reservoirs 30. Lower chamber 27communicates with reservoirs 28 disposed on the ends of haptics 26 viapassageways 29. Lower chamber 27, reservoirs 28, passageways 29 andlower relief reservoirs 30 are filled with transparent fluid 31. Theoutwardly directed surfaces of haptics 26 comprise a resilient elasticmaterial that permits force applied to those surfaces by the ciliarymuscles to cause fluid to move from reservoirs 28 through passageways 29into lower chamber 27.

Actuator element 22 comprises disk-shaped member 32 having a pluralityof cells 33 extending upwardly from its upper surface. Each cell 33illustratively comprises an annular sidewall 34 and top 35. The relativethicknesses of member 32 and sidewalls 34 and tops 35 are selected sothat when pressurized fluid is introduced into lower chamber 27, tops 35of cells 33 extend axially upward. Illustratively, cells 33 are arrangedin a ring at a predetermined radius from the optical axis of lens 20,although more or fewer cells 33 may be employed, and their locationselected to enhance deflection of layer 23, as described hereinbelow.

Anterior element 24 preferably comprises a rigid transparent material,and includes anterior lens 36, and upper relief reservoirs 37. Theinterior surface of anterior element 24 is convex and forms upperchamber 38, which accommodates upward motion of flexible layer 23, asdescribed hereinbelow. Upper relief reservoirs 37 are disposed inalignment with lower relief chambers 30 in substrate 21, outside theoptical path of anterior lens 24. Upper chamber 38 communicates withupper relief reservoirs 37 via passageways 39, and is filled withtransparent fluid 40.

Flexible layer 23 is affixed around its circumference to substrate 21and is disposed in contact with tops 35 of cells 33. Transparent fluid41 is contained within space 42 between the upper surface of actuatorelement 22 and lower surface of layer 23. Lower relief reservoirs 30communicate with space 42 via passageways 43 disposed in substrate 21. Aportion of layer 23 divides upper relief reservoirs 37 from lower reliefreservoirs 30, for purposes to be described hereinafter. Fluid 41disposed in space 42, preferably has the same index of refraction asfluid 41 in lower chamber 27, and a different index of refraction thanfluid 40 contained in upper chamber 38.

When assembled as shown in FIG. 3B and implanted into the empty capsuleof a cataract patient, compressive forces applied by the ciliary musclescause fluid 31 to move from reservoirs 28 into lower chamber 27, therebycausing tops 35 of cells 33 to extend axially upward. Upward movement oftops 35 of cells 33 in turn causes layer 23 to deflect upward anddisplace fluid 40 in upper chamber 38. Fluid displaced from upperchamber 38 flows into upper relief reservoirs 37 via passageways 39.

Simultaneously, because lower relief reservoirs 30 communicate withspace 42, fluid 41 is drawn from lower relief reservoirs 30 as layer 23is deflected upward by cells 33. Consequently, the portions of layer 23that divide upper relief reservoirs 37 from lower relief reservoirs 30serve as diaphragms that permit fluid to be simultaneously displacedinto one reservoir and withdrawn from the other. This enables fluids 40and 41 to pass freely in and out of the optical space in order tobalance relative volumes of fluid, the total volume of fluids 40 and 41remaining constant.

Movement of layer 23, and the accompanying displacement of volumes offluid 40 in upper chamber 38 with a corresponding volume of fluid 41 ofa different index of fraction in space 42, changes the opticalparameters of the lens, thereby moving the focus of the lens from nearto far or vice-versa. Posterior lens 25, which in this case comprises asolid material, also provides additional optical power. Posterior lens25 also may provide optical index dispersion so as to optimizeaberration characteristics, including wave aberration of all order, orchromatic aberration.

When the ciliary muscles relax, tops 35 of cells 33 contract, and layer23 resiliently contracts to its original position. This in turn forcesexcess fluid 41 in space 42 back into lower relief reservoirs 30. Inaddition, as the pressure in upper chamber 38 is reduced, fluid 40 isdrawn out of upper relief reservoirs 37 and into upper chamber 38.

In the embodiment of FIG. 3, fluid 31 is forced into cell 33 by ciliaryforces acting on the surface of reservoir 28, so that the actuator worksin a direction parallel to the optical axis of the lens. As will beappreciated, actuator element 22 must be index matched to fluid 31,which moves with cells 33, as well as fluid 41 that surrounds cells 33in space 42. Also in the embodiment of FIG. 3, posterior lens 25 isformed from the same material as substrate 21. Alternatively, posteriorlens 25 may comprise a different material than substrate 21, having ashape and optical parameters chosen to optimize the optical performanceof the lens system.

Relevant to the IOL of the present invention, cells 33 of the devicedepicted in FIG. 3 act not only to deflect layer 23, but also serve asfulcrum contact points. This effect is described generally with respectto FIGS. 4A-4C, wherein the effect of the placement of the fulcrumcontact points is described. Generally, fixation within the optical zoneof surface 50 (corresponding to flexible layer 23 of the embodimentdescribed hereinabove), may be accomplished in several fashionsdepending on the effect and efficiency required of the fluid forcesprovided by the fluid being moved into the chamber or cell by the forcesacting on the reservoirs in the IOL haptics.

If it is desired that surface 50 assume a flatter configuration 50′ thatprovides less optical focusing power (shown in dotted line in FIG. 4A),then fixation at fulcrum point 51 would be desired. If, on the otherhand, it is desired that surface 50 provide more power when the ciliarymuscles contract (corresponding to highly convex configuration 50″,shown in dotted line in FIG. 4B), then fixation at fulcrum points 52would be desirable.

As a further alternative, to obtain most efficient use of fluid power,e.g., to obtain maximal change in optical power for a given movement ofsurface 50 (corresponding to surface configuration 50′″ in FIG. 4C),some fixation at some intermediate fulcrum point 53 may be desired.Fulcrum point 53 also may be selected so as to minimize the change inthe volumes of the total fluid within the optical zone, therebyobviating the need for relief reservoirs to absorb excess fluid volumes.In this latter case, deflection of the flexible layer causes sufficientredistribution of the fluids within the first and second chambers toalter the power of the lens.

The foregoing discussion of fulcrum points may be advantageouslyemployed not only in a two fluid system as described in U.S. PatentPublication No. 2004/0169816 A1, but also in a system such as describedin commonly assigned U.S. Patent Publication No. 2005/0119740. In theaccommodating IOL described in that application, one or more actuatorsdisposed near the optical axis of a deformable lens element are employedto transition the lens between accommodated and unaccommodated states.

In accordance with the principles of the present invention, the fulcrumconcepts discussed above with respect to FIGS. 4A-4C are applied to alens system similar to that of U.S. Patent Publication No. 2005/0119740A1 to reduce the potential for reflections to arise from movement of theactuator disposed near the optical axis of the IOL. In particular, theactuators are moved to the periphery of the deformable lens element,while the center of the dynamic surface, along the optical axis of theIOL, is anchored to the lens substrate.

Referring now to FIGS. 5A-5D, a first embodiment of an IOL constructedin accordance with the principles of the present invention is described.IOL 60 is similar in design to the IOL of U.S. Patent Publication No.2005/0119740 A1, except that in IOL 60 the actuators are disposed at theperiphery of the anterior lens element. IOL 60 operates in the mannerdescribed for the dynamic surface of FIG. 4A, with its anterior lenselement anchored to the lens substrate. Actuation of the actuatorsdisposed at the periphery of the anterior lens element lift the edges ofthe lens element, thereby flattening the surface and reducingaccommodation of the IOL. Conversely, lowering of the periphery of theanterior lens increases convexity and accommodation of IOL 60.

As will be explained more fully below, IOL 60 assumes an accommodatedposition in its relaxed state, i.e., when no outside forces are actingon it. After implantation in a patient's eye, the IOL assumes theaccommodated configuration when the ciliary muscles contract and thecapsule relaxes. In contrast, when the ciliary muscles relax and thecapsule is pulled taut, forces applied by the capsule to the hapticcause the IOL to transition to the unaccommodated state.

IOL 60 comprises optic portion 61 and haptic portion 62. Optic portion61 includes anterior lens element 63, substrate 64 and posterior lenssurface 65. Haptic portion 62 illustratively comprises four deformabletubular members 66 mounted on extensions 67 projecting from substrate64. It should be understood that the invention may be practiced withmore or less tubular members than shown in FIG. 5.

Substrate 64 preferably comprises a sturdy transparent polymerillustratively has posterior lens surface 65 integrally formed thereon.Anterior lens element 63 is coupled to the center of substrate 64 byanchor 68, while the periphery of the lens element is sealed to the edgeof substrate 64 by sidewall 69. Anterior lens element 63 also includes aflexible circular partition 70 coupled to the substrate to defineannular chamber 71. Space 72 defined by anterior lens element 63 andsubstrate 64 inward of partition 70 preferably is filled with fluid 73,such as a silicone oil, having a refractive index that matches thesurrounding components of optic portion 61.

Substrate 64 includes one or more relief reservoirs 74 disposed near theperiphery of posterior lens surface 65 that communicate with space 72via channels 75. Substrate 64 further includes peripheral passageway 76that communicates with annular chamber 71 and the interior of tubularmembers 66 via passageways 77. The interior of tubular members 66,annular chamber 71, peripheral passageway 76 and passageways 77 all arefilled with fluid 78 having an index of refraction matched to thesurrounding components. Fluid 78 preferably, but need not be, the sameas fluid 73 in space 72.

Tubular members 66 include flexible fluid-tight endcaps 79 and areattached to extensions 67 of substrate 64 using a suitable biocompatibleadhesive, thermal bonding, or other methods known in the art. Tubularmember 66 preferably has a substantially circular cross-section in therelaxed state, i.e., when no forces are acting on it. The tubularmembers of haptic portion 62 are configured so that forces applied bythe capsule to the anterior and posterior faces of the tubular memberscauses the tubular members to transition to an ellipsoidal shape,thereby inducing fluid 78 to flow through passageways 77 and intoannular chamber 71 via peripheral passageway 76. When the lateral forcesapplied to the tubular member subside, for example, when the capsulebecomes loose as a consequence of ciliary muscle contraction, tubularmembers 66 return to their unstressed shapes, causing fluid to flow fromannular chamber 71 back to the interior of the tubular members.

In accordance with the principles of the present invention, anchor 68serves as the function of fulcrum point 51 of FIG. 4A, while annularchamber 71 serves as actuator. When fluid moves from the haptic portion62 to annular chamber 71, the periphery of the anterior lens elementlifts upwards, thereby flattening the lens surface and reducing thediopter power of the lens. To account for the increase in volume inspace 72 resulting from lifting of the edges of anterior lens element73, fluid 78 is drawn from flexible reservoirs 74 into space 72 viapassageways 75. Likewise, when the lens moves to its accommodated state,fluid 78 moves through passageways 75 back to flexible reservoirs 74.

In operation, when implanted in an eye, tubular members 66 of hapticportion 62 have a substantially circular shape when the ciliary musclesare contracted. This corresponds to the maximum volume of the interiorof tubular members 66 and the minimum volume of fluid 73 in annularchamber 71. When the ciliary muscles relax, the capsule is pulled tautby the zonules and applies compressive forces to the anterior andposterior surfaces of tubular members 66. This causes the tubularmembers to deform to a non-circular cross-section, thereby squeezingfluid into annular chamber 71. Sidewall 69 and partition 70 expandresponsive to the increased volume in annular chamber 71, therebylifting the edge of anterior lens element 63. The increased volume ofspace 72 arising from this movement is made up by transfer of fluid 78from flexible reservoirs 74 to space 72 via passageways 75. Theseactions result in IOL 60 assuming a less accommodated configuration.

When the ciliary muscles relax, tubular members 66 are no longersubjected to lateral compressive forces, and return to their unstressedgeometry. This in turn reduces the volume of fluid in annular chamber71, causing sidewall 69 and partition 70 to return to their undeformedshapes, thereby increasing the convexity of anterior lens element 63.Fluid 82 is likewise forced from space 72 between anterior lens element63 and substrate 64, through passageway 75 and back into flexiblereservoirs 74. IOL 60 thus returns to its accommodated configuration.

IOL 60 may be manufactured as described above with predetermined volumesof fluids 73 and 78. Alternatively, tubular members 66 and/or flexiblereservoirs may comprise a semi-permeable osmotic material and IOLmanufactured to contain smaller amounts of fluids 73 and 78 than may bedesired for operation of the IOL. In this alternative embodiment, IOL 60may be implanted in a slightly collapsed state, thereby facilitatinginsertion. Subsequently, the osmotic gradient may cause water in the eyeto permeate the tubular member and/or flexible reservoirs to increasethe volume of fluids 73 and 78 to provide correction functioning of IOL60.

Referring now to FIG. 6, an alternative embodiment of an IOL of thepresent invention is described. Like the embodiment of FIG. 5, IOL 80also has the center of the anterior lens element fixed to the substrate,so that the edges of the lens element lift to transition the IOL to theunaccommodated state.

IOL 80 assumes an accommodated position when no outside forces areacting on it. After implantation in a patient's eye, the IOL assumes theaccommodated configuration when the ciliary muscles contract. Incontrast, when the ciliary muscles relax and the capsule is pulled tautby the zonules, the capsule applies forces to the haptic portion of theIOL, which in turn causes the IOL to transition to the unaccommodatedstate.

IOL 80 comprises optic portion 81 and haptic portion 82. Optic portion81 shapes and focuses light on the optic nerve while haptic portion 82orients and supports the IOL with the capsule and actuates theaccommodating mechanism of the IOL. As depicted in FIG. 6C, IOL 80illustratively comprises anterior portion 83 affixed to posteriorportion 84.

Anterior portion 83 comprises a flexible optically transparent materialthat forms anterior lens element 85. Anterior lens element 85 includesanchor 86 that extends posteriorly from the center of the lens element85. Lens element 85 is coupled around its edge 87 to haptic half 88 byflexible membrane 89. Spacers 90 also extend posteriorly from theinterior surface of anterior portion 83. Posterior portion 84 comprisessturdy optically transparent polymer substrate 91, posterior lenssurface 92 and posterior haptic half 93, peripheral step 94 andreceptacle 95.

Anterior portion 83 is configured to attach to posterior portion 84 sothat anchor 85 is fixedly received within receptacle 95, spacers 90 seatagainst peripheral step 94, and posterior haptic half 93 sealingly mateswith anterior haptic half 88, as depicted in FIG. 6B. When so assembled,haptic halves 88 and 93 form chamber 96 that communicates with space 97between anterior lens element 85 and substrate 92 through channels 98disposed between spacers 90. The interior volume of the IOL, includingchamber 96 and space 97, is filled with transparent fluid 99, which hasan index of refraction selected to match the index of refraction of thesurrounding components of IOL 80. Flexible membrane 89 allows edge 87 ofanterior lens element 84 to move away from substrate 91 responsive topressure variations in haptic portion 82.

In accordance with the present invention, haptic halves 88 and 93 ofhaptic portion 82 comprise a resilient elastic material that permitsforce applied to those surfaces to the haptic portion to deform.Preferably, when the ciliary muscles contract, the haptic portion is inan unstressed state and assumes a substantially circular cross-section.This corresponds to a maximum internal volume of chamber 96 and aminimum volume of space 97.

When the ciliary muscles relax, the zonules pull the capsule taut,thereby applying compressive forces to the anterior and posterior facesof the haptic portion which in turn cause fluid 99 to pass from chamber96 through channels 98 and into space 97. Fluid entering space 97 causesedge 87 of anterior lens element 85 to lift in the anterior direction,thereby reducing the convexity of the anterior lens element and reducingthe diopter power of the lens. The flexible nature of membrane 89permits edge 87 to freely deflect when the volume of space 97 increases.

The volume of fluid 99 preferably is selected so that when no externalpressure is applied to IOL 80, fluid 99 fills the interior of the IOLand anterior lens element 85 has its most convex shape. Therefore, whenpressure is applied to haptic portion 82, fluid 99 migrates beneathanterior lens element 85 to cause IOL 80 to transition to theunaccommodated state.

In addition, the anterior surface of substrate 91 preferably has apredetermined anterior profile, so that in the event of a loss of fluid99 from the IOL, e.g., resulting in a failure of a seal, the IOLconforms to the anterior profile of the substrate and thus stillprovides the patient with a desired degree of correction. In a preferredembodiment, substrate 91 is symmetrical, such that peripheral step 94has a uniform depth. In this case, anterior portion 81 may be attachedto substrate 91 at any relative rotational angle.

Anterior lens element 85 may have a constant thickness from the centerto the outer edge, or a variable thickness. For example, the anteriorlens element may be thinner near anchor 86 with an increasing thicknesstoward edge 87. Alternatively, the anterior lens element may be thickernear the anchor with a decreasing thickness toward edge 87.

While preferred embodiments of the present invention have been shown anddescribed herein, it will be obvious to those skilled in the art thatsuch embodiments are provided by way of example only. Numerousvariations, changes, and substitutions will now occur to those skilledin the art without departing from the invention. It should be understoodthat various alternatives to the embodiments of the invention describedherein may be employed in practicing the invention. It is intended thatthe following claims define the scope of the invention and that methodsand structures within the scope of these claims and their equivalents becovered thereby.

What is claimed is:
 1. An accommodating intraocular lens comprising: anoptic comprising a flexible anterior element, a posterior element, anoptical axis, the flexible anterior element is the most anterior aspectof the accommodating intraocular lens along the optical axis, theflexible anterior element and the posterior element at least partiallydefining an optic fluid chamber disposed between the flexible anteriorelement and the posterior element; a haptic portion peripheral to theoptic and configured to deform in responsive to ciliary muscle movement,the haptic portion comprising at least one haptic fluid chamber in fluidcommunication with the optic fluid chamber; and a fluid disposed withinthe optic fluid chamber and the at least one haptic fluid chamber,wherein the fluid is adapted to be moved between the at least one hapticfluid chamber and the optic fluid chamber in response to deformation ofthe haptic portion, and wherein a periphery of the flexible anteriorelement is adapted to be displaced more than a portion of the flexibleanterior element disposed along the optical axis in response to movementof the fluid.
 2. The intraocular lens of claim 1 wherein the opticportion further comprises an anchor disposed along the optic axis. 3.The intraocular lens of claim 1 wherein the fluid has an index ofrefraction that is substantially the same as an index of refraction ofthe anterior element and an index of refraction of the posteriorelement.
 4. The intraocular lens of claim 1 wherein the intraocular lenshas an accommodated state in which the flexible anterior element assumesa convex shape and an unaccommodated state in which the periphery of theflexible anterior element is displaced relative to the flexible anteriorelement along the optical axis to render the flexible anterior elementless convex.
 5. The intraocular lens of claim 1 wherein the hapticportion comprises a first haptic with a first haptic fluid chamber and asecond haptic with a second haptic fluid chamber, the first and secondfluid chambers in fluid communication with the optic fluid chamber.